Water end assembly of a servo-fuel control



United States Patent 72] Inventors Thomas F; Cook Arlington Heights;

Stanley E. Dybczak, Des Plaines; Raymond P. Czarnecki, Elk Grove Village, Illinois 717,754

April 1, 1968 Oct. 6, l 970 Vapor Corporation Chicago, Illinois a corporation of Delaware [21] Appl. No. [22] Filed [45] Patented [73] Assignee [54] WATER END ASSEMBLY OF A SERVO-FUEL CONTROL 1 Clalm, 1 Drawing Fig.

[52] US. Cl 91/401, 251/122 [51] Int. Cl F1511 15/22 [50] Field ol'Search 137/494,

504,503;25l/61.1,6l.5,61,61.2,6l.3,61.4; 251/45,46;9l/401,4l0

[56] References Cited UNITED STATES PATENTS 1,627,312 5/1927 Blust l37/504X 1,851,062 3/1932 Protzer 251/46 2,740,604 4/1956 Swigan et al 251/613 3,035,408 5/1962 Silver 251/46X 3,156,258 11/1964 Moody 137/504 3,422,842 H1969 Erickson 137/504 Primary Examiner-M. Cary Nelson Assistant ExaminerRobert J. Miller A trorney- Norman Aon Witt ABSTRACT: Water end assembly of a servo-fuel control for a steam generator, wherein the assembly includes a coacting metering pin and collar operated by a rolling diaphragm mounted on a piston.

Patented Oct. 6, 1970 INVENTORS THOMAS P. COOK STANLEY E. DYBCZAK RAYMOND P. CZARNECKI BY \(Qlfu-m. 4 .011 1 k ATTORNEY WATER END ASSEMBLY OF A SERVO-FUEL CONTROL This invention relates in general to steam generators, and more particularly to a servo-fuel control for a steam generator sprayhead, and still more particularly to a water end assembly of a servofuel control.

A servo-fuel control comprises a hydraulically operated device for metering fuel to a steam generator sprayhead and regulating the amount of combustion air delivered to the firepot of the generator. The fuel is metered in direct proportion to the amount of feed water flowing to the generator. The servo-fuel control includes two mechanically coupled devices in a fuel end assembly that regulates the flow of fuel and air to the steam generator, and a water end assembly that controls the operation of the fuel end assembly in direct relation to the amount of feed water flowing through the servo control. This invention relates only to the water end assembly.

A water end assembly ofa fuel-servo control is subjective to the flow of hot water therethrough, and heretofore early failure has caused the malfunctioning of many servo-fuel controls. The water end assembly of the present invention increases the output of a generator because of its structure and components, reduces maintenance of servo-fuel controls, and permits a generator to be piped formore reliable operation.

A rolling diaphragm is provided in the water end assembly of the present invention having a large portion of the diaphragms effective area supported by a piston. Low diaphragm fiber stresses result, and are kept to a minimum because of the support by the piston thereby obtaining longer diaphragm life. Preferably the diaphragm material choice is highly resistant to water temperatures up to 220F, thereby permitting the generator to be piped to include the heat exchanger aheadof rather than behind the servo-fuel control. This allows the servo-fuel control to detect a decrease of water flow to the generator due to a leak in the heat exchanger, thereby resulting in increased generator reliability.

Accordingly, it is an object of the present invention to provide an improved water end assembly for a servo-fuel control of a steam generator which will increase generator output,

reduce maintenance of the fuel-servo control and allow the generator to be piped for more reliable operation.

Another object of this invention resides in the provision ofa water end assembly for a servo-fuel control that includes a rolling diaphragm which does not flex as it completes its stroke, thereby placing no restriction on the movement of the diaphragm.

Other objects, features and advantages of the invention will be apparent from the following detailed disclosure, taken in conjunction with the accompanying sheet of drawing, wherein like reference numerals refer to like parts, in which:

The single figure is an axial sectional view taken through the water end assembly according to the present invention.

The water end assembly of the present invention includes a housing comprised of a central cylinder section having upper and lower flange surfaces 11 and 12. an operator rod section 13 having a flange surface 14 and being mounted on top of the cylinder section 10, and a diaphragm cover section 15 having a flange surface 16 and mounted on the bottom of the cylinder section 10.

A piston 17 is freely received within the cylinder section 10, and has secured thereto a rolling diaphragm 18 by a diaphragm retainer plate 19. The periphery of the rolling diaphragm I8 is secured between and seals the lower flange surface 12 of the cylinder section 10 and the flange surface 16 of the diaphragm cover section 15. A gasket 20 seals between the upper flange surface 11 of the cylinder section 10 and the flange surface 14 of the operator rod section 13. A suitable number of fastening bolts 21 secure the cylinder, operator rod and diaphragm cover sections together.

The piston 17 and the diaphragm 18 separate the compartment within the housing to define an upper diaphragm chamber 22 and a lower. diaphragm chamber 23. An inlet 24 is provided in the diaphragm cover section 15 to directly communicate with the lower diaphragm chamber 23 while an outlet 25 is provided in the operator rod section 13 to directly communicate with the upper diaphragm chamber 22.

A metering collar 26 18 mounted centrally of the piston 17 and provided with a circular metering opening or passageway 27. Coacting with the metering opening 27 is a metering pin or needle 28 having a tapered or conical surface 29 which directly coacts with the inlet end 27a of the metering opening 27 in metering water flow through the assembly from the inlet 24 through the lower diaphragm chamber 23, the upper diaphragm chamber 22 and out the outlet 25. At the lower end of the conical surface 29, a cylindrical surface 30 is defined that can snugly mate with the metering opening 27. The lower end of the cylindrical surface 30 terminates at a shoulder 31 upon which the piston rests during a no flow condition.

The metering pin 28 is provided with a threaded stud 32 that is threadedly received in an adapter fitting 33. The adapter fitting is in turn threadedly received in a tapped opening formed in the diaphragm cover section 15. Thus, the metering pin may be easily removed from the assembly for servicing. Shims 34 are provided between the metering pin and the adapter fitting for initially adjusting the assembly to obtain the correct start-up position of the diaphragm 18. Thus, movement of the piston and diaphragm controls the flow of feed water through the assembly and responds to the pressure of the feed water in the lower diaphragm chamber 23.

An operator rod 35 is mounted in the operator rod section 13 and adapted to be coupled to the fuel end assembly of the servo-fuel control. The rod is drivingly connected to the piston 17 by a crank arm 36 arranged within the operator rod section and secured to an inner end of the rod, a pin 37 at the outer end of the crank 36, and a piston yoke 38 that is pivotally carried on the pin 37 and suitably secured to the piston 17, such as by brazing or the like. Thus, movement of the piston and diaphragm in turn causes rotation of the operator rod 35. A clock spring 39 is provided on the operator rod 35 to continually apply a tension to the operator rod opposed to movement of the piston and diaphragm as caused by the pressure of the feed water in the lower diaphragm chamber 23.

In operation, as feed water pressure builds-up in the lower diaphragm chamber 23, the piston and diaphragm are moved upwards thereby allowing feed water flow through the assembly and actuation of the operator rod 35. Nearly frictionless rolling action of the diaphragm results as the piston 17 moves upwardly or downwardly. The height to which the diaphragm is lifted by the pressure of the feed water and flow of the feed water through the assembly is directly proportional to the flow area between the metering pin 28 and the metering collar 26. Since the rolling diaphragm 18 does not flex during its stroke, no restriction is placed on the movement of the diaphragm and piston.

It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention.

We claim:

1. A water end assembly for a servo-fuel control comprising, a housing having an inlet and an outlet and a compartment therebetween, a piston within said compartment, an operating rod extending from said housing and being drivingly connected to said piston, a rolling diaphragm mounted on said piston and secured to the housing to define in the compartment upper and lower diaphragm chambers, one of said chambers directly communicating with said inlet and the other of said chambers directly communicating with said outlet, a metering opening in said piston defined by a metering collar fixed to the piston, a conically shaped fixed metering pin mounted in said housing within said chamber communicating with the inlet and with its small end extending into and coacting with said metering opening to regulate the flow of water therethrough and having a shoulder against which the metering collar rests when in closed position, and resilient means biasing said piston toward closing of said metering opening with said metering pin, whereby the flow of water through said assembly and movement of said piston and diaphragm means responds to the pressure at the inlet to modulate the operating rod position. 

